Generally, a washing machine is a generic name for electric home appliances that wash, dry, or wash and dry laundry.
The washing machine is mainly classified as an agitator type washing machine, a pulsator type washing machine, or a drum type washing machine.
In the agitator type washing machine, a washing rod vertically mounted in the middle of a washing tub is rotated in alternating directions to wash laundry in the washing tub. In the pulsator type washing machine, a disc type rotary blade mounted at the bottom of a washing tub is rotated in alternating directions to wash laundry using a water stream generated in the washing tub. In the drum type washing machine, a drum, mounted in a tub having wash water contained therein, is rotated to wash the laundry.
The drum type washing machine includes a tub mounted in a cabinet forming the external appearance of the washing machine for containing wash water, a drum mounted in the tub for containing laundry, and a motor and a shaft mounted to the rear of the tub for rotating the drum.
Upon commencement of washing in the drum type washing machine with the above-stated construction, the amount of laundry (hereinafter, referred to as ‘laundry amount’) placed in the drum is determined, and control data necessary to control the washing machine are set. That is, the amount of wash water to be supplied, the amount of detergent necessary, an actual operation ratio of the motor, and operation time of the washing machine are set based on the laundry amount.
When the laundry amount is incorrectly determined, incorrect control data are set, and the washing machine is operated based on the incorrect control data. For the washing machine, therefore, determination of the laundry amount is very important.